Diazepines, Smiles rearrangement

Intramolecular cyclisation of the azides (79) by refluxing in toluene has produced the [ 1,2,3]triazolo[ 1,5-u][ 1,4]diazepines (80) <95S647>. Removal of the Boc protecting group in the benzodiazepine derivative (81), prepared in three steps from 2-fluoro-5-nitro-benzoic acid, results in ring expansion to (82) via a Smiles rearrangement <95SL539>. 

The cyclization reaction of 39 under basic conditions furnished a 1 1 mixture of diazepines 40 and 43. The unexpected formation of 43 has been rationalized by a Smiles rearrangement involving a nucleophilic attack of the deprotonated 3 -nitrogen at position 4 of the second pyridazine ring resulting in the displacement of a carboxamide anion followed by cyclization to afford 43. ... 

The nucleophilic substitution of the pyrimidine 168 by N-benzylglycinol afforded 169, which was then oxidised under Parikh-Doering conditions to give the aldehyde 170. Then 170 underwent cyclization to give hydroxydiazepine 171. When the aldehyde 170 upon treatment with para-toluidine under Pictet-Spengler cyclization reaction conditions afforded the diazepine 172, which was labile and quickly imderwent Smiles rearrangement to afford 173. " ... 

In a complex series of transformations, reaction of the diene (36) with 1,4-diaminobutane results in the formation of the bicyclic pyrido[l,2-a][l,3]diazepine (37) in what is a formal insertion of a Cl fragment into the diamine <95JHC477>. Initial nucleophilic replacement of the thiomethyl group by the diamine and subsequent cyclization is followed by a Smiles-type rearrangement, then sequential ring-opening and ring-closure transformations. 

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See also in sourсe #XX -- [ ]

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